package lock;

import java.util.Random;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * Created by wangyg 
 * on 2017/3/27 11:32
 */
public class ReadWriteLockTest {
	public static void main(String[] args) {
		final Operation o = new Operation();
		for(int i=0; i<3; i++) {
			new Thread(){
				public void run(){
					while(true){
						o.get();
					}
				}
			}.start();

			new Thread(){
				public void run(){
					while(true){
						o.put(new Random().nextInt(10000));
					}
				}
			}.start();
		}
	}
}

class Operation{
	//共享数据，只能有一个线程能写该数据，但可以有多个线程同时读该数据。
	private Object data = null;
	ReadWriteLock rwl = new ReentrantReadWriteLock();

	public void get(){
		rwl.readLock().lock();
		try {
			System.out.println(Thread.currentThread().getName() + " be ready to read data!");
			Thread.sleep((long)(Math.random()*1000));
			System.out.println(Thread.currentThread().getName() + " have read data :" + data);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}finally{
			rwl.readLock().unlock();
		}
	}

	public void put(Object data){
		rwl.writeLock().lock();
		try {
			System.out.println(Thread.currentThread().getName() + " be ready to write data!");
			Thread.sleep((long)(Math.random()*1000));
			this.data = data;
			System.out.println(Thread.currentThread().getName() + " have write data: " + data);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}finally{
			rwl.writeLock().unlock();
		}
	}
}

